Continuous casting of metal melts



Jan. 24, 1967 K. BROTZMANN CONTINUOUS CASTING OF METAL MELTS 2 Sheets-Sheet '1 Filed Jan. 17, 1964 I m F INVENTOR K. BRQTZMANN CONTINUOUS CASTING OF METAL MELTS Filed Jan. 17, 1964 2 Sheets-Sheet Z IN VEN TOR United States. Patent 3,299,481 CONTINUOUS CASTING 0F METAL MELTS Karl Brotzmann, Westhofen-Buchholz, near Schwerte (Ruhr), Germany, assignor to Dortmund-Border Huttenuuion Aktiengesellschaft, Dortmund, Germany, a corporation of Germany Filed Jan. 17, 1964, Ser. No. 338,343

Claims priority, application Germany, Jan. 25, 1963,

2 Claims. (Cl. 22-200.1)

In continuous casting the supply of molten metal must satisfy a number of requirements which are diflicult to fulfill in practice. Firstly, the metal must flow to the casting mould in a quantity such that the optimum rate of descent of the casting can be maintained. Moreover, since the molten metal is supplied to the mould intermittently from ladles, a reservoir must be interposed between the ladle and the mould to bridge over the pauses in the supply of metal and ensure a continuous supply to the mould. Another important problem in continuous casting arises from the fact that the relatively long pouring time causes considerable temperature losses which necessitate superheating of the metal or extra heating in the supply ducts to the mould. Moreover, as the poured metal flows to the mould, the metal must not suffer any changese.g., by oxidation through contact with the air or as a result of reactions with the slag or the thermally insulating covers. Finally, easy and reliable control of the flow of metal to the mould must be provided. Known methods of continuously casting metal melts do not meet these requirements entirely satisfactorily. In accordance with the present invention, metal melts are continuously cast by a method in which molten metal is poured intermittently from a ladle into a reservoir from which the metal runs continuously into one or more moulds, wherein a space in the reservoir above the level of the metal melt is sealed from the atmosphere and is evacuated as each charge of metal is poured into the reservoir so that the level of the melt in the reservoir rises higher than it would otherwise do to take up the bulk of the charge, the pressure in the space being subsequently increased gradually before the next charge of metal is poured into the reservoir so that the metal running from the reservoir into the mould or moulds is under a substantially contstant pressure head. The substantially constant pressure head under which the metal runs from the reservoir into the mould or moulds may itself be controlled by controlling the pressure in the space above the metal space in the reservoir. The invention also includes apparatus for carrying out the above novel method, the apparatus comprising an open topped trough permanently in communication with the lower part of a reservoir for the metal melt, the reservoir having at its bottom one or more outlets for supplying molten into a corresponding mould or moulds and its upper part closed except for a duct leading to a vacuum pump.

Advantageously, the novel method is carried out by means of an apparatus in which the reservoir is in permanent communication with an open topped trough which is open to the atmosphere and receives the poured melt. The bottom of the reservoir is formed with pouring apertures corresponding to the number of moulds used. The upper part of the reservoir is connected through a duct to a vacuum pump.

One example of an apparatus for carrying out the method according to the invention is illustrated in the accompanying drawings, in which:

FIGURE 1 is a vertical section through the apparatus, a ladle, and an ingot mould;

FIGURE 2 is a horizontal section through the apparatus; and,

FIGURE 3 is a section taken along the line AA in FIGURE 1.

3,299,431 Patented Jan. 24, 1967 As shown in FIGURE 1, the metal melt is poured from a ladle 1 into a trough 2 which is in permanent communication with the bottom of a reservoir 3. The reservoir is connected by an evacuation spigot 4 to a vacuum pump 5. The molten metal runs through two pouring outlets 6 in the reservoir bottom into two ingot moulds 7 and 8. The quantity of molten metal passing through the pouring aperture 6 per unit of time is determined by the pressure head above the outlets 6, that is on the height H of metal between the surface of the bath open to the atmospheric air in the trough 2 and the discharge end of the pouring outlets 6. When the space above the metal in the reservoir 3 is at normal atmospheric pressure, the bath surfaces in the trough 2 and the reservoir 3 are at the same level. The speed of pouring into the trough 2 and the casting speed would then have to be identical to keep the bath level H and therefore the speed of casting into the ingot mould constant. However in accordance with the invention, the additional supply of molten metal required to maintain the supply of metal during the pauses in delivery of metal from the ladle 1 into the trough 2 is created while maintaining the bath level H in the trough 2, by the fact that a quantity of molten metal in excess of the casting speed is poured into the trough 2, the gas pressure at the top of the reservoir 3 being reduced simultaneously. The level of metal in the reservoir 3 therefore rises by the lever 11 where the head h of metal plus the pressure in the top of the reservoir balances atmospheric pressure. With a reservoir of 2 in. internal diameter and a level 11 of l m. the additional amount of molten metal is approximately 30 tons. After the ladle has been emptied the pressure in the top of the reservoir 3 is gradually allowed to increase so that the bath level H and therefore the casting speed remain un changed.

Any increase in the speed of increasing or lowering the pressure causes a change in the bath level H and therefore enables the casting speed to be regulated as required at any time.

A carbon-rod heating element 10 maintains a reducing atmosphere in the reservoir 3. The carbon-rod may have a heat dissipation of approximately 400 kw. and can therefore compensate for a temperature loss of 25 C. at a casting speed of 60 tons per hour.

As illustrated in FIGURE 3, the reservoir 3 is arranged to rotate around a pivot 9 disposed below the pouring apertures so that a different amount of molten metal can be poured into the two ingot moulds 7, 8 if required. When the reservoir 3 occupies the position illustrated in chain-dotted lined a greater quantity of molten metal is supplied to the mould 7 than to the mould 8.

The method is not adversely effected by high temperature losses and, more particularly, it provides uniform continuous casting despite interruptions in the supply of molten metal. Any reactions between the molten metal and slag or coverings are obviated and so, to a great extent, is oxidation by the atmospheric air. The apparatus for the performance of the method is very simply constructed. No plugs which might interfere with casting are associated with the pouring apertures. The refractory linings are easily accessible so that any necessary repairs can be carried out without difiiculty and at a low cost.

I claim:

1. Method of continuously casting molten metal which comprises intermittently introducing charges of molten metal from a succession of ladles into the open trough of a reservoir discharging the molten metal continuously into at least one mold, evacuating a space sealed from the atmosphere and located in contact with and above the level of the molten metal in the reservoir as each charge of molten metal is introduced into the trough so that the level of the molten metal contacting said space rises higher than if the space were maintained under normal atmospheric pressure, whereby a plurality of charges of molten metal may be accumulated in the reservoir, gradually increasing the pressure in the space before each succeeding charge of molten metal is introduced into the trough so that the molten metal discharging from the reservoir into the mold is under a substantially constant pressure head even during the intervals between successive charging of the reservoir with the molten metal and is continuously discharged from the reservoir at substantially constant velocity.

2. Method according to claim 1, which includes regulating the substantially constant pressure head under which References Cited by the Examiner UNITED STATES PATENTS 3,179,512 4/1965 Olsson 22-73 J. SPENCER OVERI-IOLS ER, Primary Examiner.

V. K. RISING, Assistant Examiner. 

1. METHOD OF CONTINUOUSLY CASTING MOLTEN METAL WHICH COMPRISES INTERMITTENTLY INTRODUCING CHARGES OF MOLTEN METAL FROM A SUCCESSION OF LADLES INTO THE OPEN TROUGH OF A RESERVOIR DISCHARGING THE MOLTEN METAL CONTINUOUSLY INTO AT LEAST ONE MOLD, EVACUATING A SPACE FROM THE ATMOSPHERE AND LOCATED IN CONTACT WITH AND ABOVE THE LEVEL OF THE MOLTEN METAL IN THE RESERVOIR AS EACH CHARGE OF MOLTEN METAL IS INTRODUCED INTO THE TROUGH SO THAT THE LEVEL OF TH MOLTEN CONTACTING SAID SPACE RISES HIGHER THAN IF THE SPACE WERE MAINTAINED UNDER NORMAL ATMOSPHERIC PRESSURE, WHEREBY A PLUALITY OF CHARGES OF MOLTEN METAL MAY BE ACCUMULATED IN THE RESERVOIR, GRADUALLY INCREASING THE PRESSURE IN THE SPACE BEFORE EACH SUCCEEDING CHARGE OF MOLTEN METAL IS INTRODUCED INTO THE TROUGH SO THAT THE MOLTEN METAL DISCHARGING FROM THE RESERVOIR INTO THE MOLD IS UNDER A SUBSTANTIALLY CONSTANT PRESSURE HEAD EVEN DURING THE INTERVALS BETWEEN SUCCESSIVE CHARGING OF THE RESERVOIR WITH THE MOLTEN METAL AND IS CONTINUOUSLY DISCHARGED FROM THE RESERVOIR AT SUBSTANTIALLY CONSTANT VELOCITY. 